• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1343-1354
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• 2007

Secondary batteries become more important in our lives as the use of portable electric devices, such as camera, cellular phone, laptop, etc. Especially, because of their high energy densities and high voltage, lithium-ion batteries are being used in many systems. For the optimum design of such systems which include lithium-ion batteries, virtual prototype is required generally. However, since the complex chemical and physical processes are involved, the behavior of battery becomes harder to be predicted compared with that of electric and mechanic devices. This paper, proposes a new static model of lithium secondary battery, which accounts for nonlinear equilibrium potentials, rate and temperature dependencies, thermal effects, lifetime characteristic. The results of the simulation of the model are analysed and compared with experimental data to inspect their validity.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.2
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• pp.127-132
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• 2024

Recently, secondary batteries, commonly known as rechargeable batteries, find widespread applications across various industries. Particularly valued for their compact and lightweight characteristics, they play a crucial role in diverse portable electronic devices such as smartphones, laptops, and tablets, offering high energy density and efficient charge-discharge capabilities. Moreover, they serve as vital components in electric vehicles and contribute significantly to the field of renewable energy as part of Energy Storage Systems(ESS). However, despite advancements in this technology, issues such as reduced lifespan, cracking, damage, and even the risk of fire can arise due to excessive charging and discharging of secondary batteries. To address these challenges, Battery Management System(BMS) are employed to protect against overcharging and improve overall performance. Nevertheless, understanding the protective range settings of BMS using lithium-ion batteries, the most commonly used secondary batteries, and lead-acid batteries can be challenging. Therefore, this paper aims to utilize a battery charge-discharge tester and simulator to investigate the charging and discharging characteristics of lithium-ion batteries and lead-acid batteries, addressing the associated challenges of reduced lifespan, cracking, damage, and fire hazards in secondary batteries.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.6
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• pp.328-334
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• 2000

A lithium ion secondary battery using carbon as a negative electrode has been developed. Further improvements to increase the cell capacity are expected by modifying the structure of the carbonaceous material. There are hopes for the development of large capacity lithium ion secondary batteries with long cycle, high energy density, high power density, and high energy efficiency. In the present paper, needle cokes from petroleum were examined as an anode of lithium ion secondary battery. Petroleum cokes, MCL(Molten Caustic Leaching) treated in Korea Institute Energy Research, were carbonized at various temperatures of 0, 500, 700, $19700^{\circ}C$ at heating rate of $2^{\circ}C$/min for lh. The electrolyte was used lM liPF6 EC/DEC (1:1). The voltage range of charge & discharge was 0.0V(0.05V) ~ 2.0V. The treated petroleum coke at $700^{\circ}C$ had an initial capacity over 560mAh.g which beyond the theoretical maximum capacity, 372mAh/g for LiC6. This phenomena suggests that carbon materials with disordered structure had higher cell capacity than that the graphitic carbon materials.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.128.2-128.2
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• 2007

• Carbon letters
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• v.5 no.3
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• pp.118-126
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• 2004

MCMB (Mesocarbon microbeads) is a kind of anode material for lithium-ion secondary battery. MCMB charge/discharge cycle stability is one of the important criterion at lithium-ion battery operation. In this study, the cycling stability of a lithium-ion secondary battery has been examined. MCMB was made by the direct solvent extraction method. After the MCMB was carbonized and graphitized, the measurement of charge/discharge capacity and efficiency were carried out. In the result, discharge capacity of MCMB in the initial cycle was above 290.0 mAh/g. After the second cycle, efficiency of charge/discharge MCMB was about 98%. These results were similar to the commercial MCMB product.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.4
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• pp.171-176
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• 2023

In the modern society of the 21st century, portable electronic products using secondary batteries are continuously becoming lightweight and miniaturized. And along with this trend, we are active in the era of the Fourth Industrial Revolution, where we collect and share information in our daily lives using wearable electronic devices. Therefore, the role of secondary batteries that can be recharged while using small home appliances and digital devices is increasingly important. Along with this increase, secondary battery performance tests require various test methods such as characteristics, lifespan, failure diagnosis, and recycling. In addition, the construction of a battery test system to ensure the safety and proper functioning of the battery, along with guidelines and correct basic knowledge are being considered. Therefore, in this paper, we will examine the characteristics of the secondary battery Li-ion battery according to the charging and discharging scenarios directly connected to the performance of the battery.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.786-790
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• 1998

K-GIC of the new carbon electrode to improve performance of carbon negative electrode in lithium ion secondary battery was prepated and its electrical characteristics were studied. Form this study, intercalated K quantity was increased in order of $2>3>1mole/{\ell}$ of KCl solution. And, for KCl solution of 1mole, the mole ratio of carbon and potassium was 156~388 carbon/potassium. The proper condition of K-GIC preparation was KCl solution of $1mole/{\ell}$, reaction temperature of $700^{\circ}C$, reaction time of 1 hour. From this condition, the intercalation and deintercalation behavior of lithium was very excellent. Also the reversibility was excellent.

• Journal of Electrochemical Science and Technology
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• v.13 no.3
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• pp.323-338
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• 2022

Heat generation and temperature of a battery is usually presented by an equation of current. This means that we need to adopt time domain calculation to obtain thermal characteristics of the battery. To avoid the complicated calculations using time domain, 'state of charge (SOC)' can be used as an independent variable. A SOC based calculation method is elucidated through the comparison between the calculated results and experimental results together. Experiments are carried for rapid resistive discharge of a large-capacitive lithium secondary battery to evaluate variations of cell potential, current and temperature. Calculations are performed based on open-circuit cell potential (SOC,T), internal resistance (SOC,T) and entropy (SOC) with specific heat capacity.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.631-636
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• 2018

This paper proposed an optimal operation strategy for a hybrid energy storage system (HESS) with a lithium-ion battery and lead-acid battery for mild hybrid electric vehicles (mild HEVs). The proposed mild HEV system is targeted to mount the electric motor and the battery to a conventional internal combustion engine vehicle. Because the proposed mild HEV includes the motor and energy storage device of small capacity, the system focuses on low system cost and small size. To overcome these limitations, it is necessary to use a lead acid battery which is used for a vehicle. Thus, it is possible to use more energy using HESS with a lithium battery and a lead storage battery. The HESS, which combines the lithium-ion battery and the secondary battery in parallel, can achieve better performance by using the two types of energy storage systems with different characteristics. However, the system requires an operation strategy because accurate and selective control of the batteries for each situation is necessary. In this paper, an optimal operation strategy is proposed considering characteristics of each energy storage system, state-of-charge (SOC), bidirectional converters, the desired output power, and driving conditions in the mild HEV system. The performance of the proposed system is evaluated through several case studies with respect to energy capacity, SOC, battery characteristic, and system efficiency.

• Journal of the Korean Applied Science and Technology
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• v.20 no.2
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• pp.130-140
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• 2003

In order to improve the lithium ion battery's performance, the carbon nanofibers were introduced to the anode electrode fabricated with natural graphite particles. The influence of structural adjustment of the particles by the introduction method of carbon nanofibers and the content of carbon nanofibers on the electrical property and charge/discharge characteristics of the electrode were investigated. The electrode fabricated with the mixture of 10 wt% of carbon nanofibers grown separately and 90 wt% of graphite particles showed an excellent discharge capacity of 400 mAh/g and the improved cycle performance. The improved performance could be explained by that the carbon nanofibers shortened and uniformly distributed on the surface of graphite particles by ball milling increased the stability for the intercalation/deintercalation of lithium ion and increased the electrical conductivity due to the closed packing between graphite particles.